FPGA Based Implementation of Encryption and Decryption of 16-Bit Data Using VHDL

FPGA Based Implementation of Encryption and Decryption of 16-Bit Data Using VHDL

Paresh Kumar Pasayat, Janmejaya Rout, Kodanda Dhar Sa

Abstract: This paper deals with the techniques used for encoding of 16-bit data known as encryption and decoding of the encoded data to get the original 16-bit data known as decryption. The encryption and decryption processes are carried out by taking two chip codes each having 8-bit.The goal has been achieved by doing different operations on the input data, chip code and encoded data. This technique can be used in the field of wireless communication with error free transmission and reception of data from source and destination.

Key words: Encryption, decryption, chip code VHDL (Very High speed Integrated Circuit Hardware Description Language).

1. Introduction: The transformation of original data into an unreadable format is known as called encryption and the process of reversing it back to a readable form is known as decryption. The encryption and decryption of 16-bit data can be used in the digital communication technology for error free data transmission from one point to another point and to provide security to the data to achieve the confidentiality in data transmission.

2. Description & Architecture: In order to encrypt the 16-bit data, the following steps are used.

   Step 1: The input data having 16-bit (say I) is divided into two parts (I_1 & I_2) each having 8-bit.

   Step 2: The two datas I_1 & I_2 are used to perform the XOR operations with the two chip codes ( C_1 & C_2) resulting two outputs such as E_XOR_1 & E_XOR_2.i.e. E_XOR_1 = I_1 xor C_1

   E_XOR_2 = I_2 xor C_2

   Step 3: The results obtained after performing the xor operations are undergone for 1s complement operations resulting E_C_1 & E_C_2.

   E_C_1 = not E_XOR_1 E_C_2 = not E_XOR_2

   Step 4: The complemented outputs are used to perform left rotate operation where the datas are rotated by one bit towards left giving rise to two outputs such as E_LR_1 & E_LR_2.

   E_LR_1 = E_C_1(0) & E_C_1(7 downto 1) E_LR_2 = E_C_2(0) & E_C_2(7 downto 1)

   Step 5: The results having two 8-bit datas obtained after the left rotate operations are appended to get the 16-bit encoded data known as cipher data (say CIPHER_DATA).

   CIPHER_DATA = E_LR_1 & E_LR_2

   16 bit Input Data

   Figure 1: Block diagram of the encryption process

   In order to decrypt the 16-bit cipher data, the following steps are used.

   Step 1: The cipher data having 16-bit is divided into two parts (C_DATA_1 & C_DATA_2) each having 8-bit.

   Step 2: The outputs obtained after the bit separation are used to perform right rotate operations where the datas are rotated by one bit towards right giving rise to two outputs such as D_RR_1 & D_RR_2.

   D_RR_1 = C_DATA_1 (6 downto 0) & C_DATA_1 (7)

   D_RR_2 = C_DATA_2 (6 downto 0) & C_DATA_2 (7)

   Step 3: The results obtained after performing the right rotate operations are undergone for 1s complement operations resulting D_C_1 & D_C_2.

   D_C_1 = not D_RR_1 D_C_2 = not D_RR_2

   Step 4: The two datas resulted from the complementary operations are used to perform the XOR operations with the two chip codes which should be same as the chip codes used during the encryption of data resulting two outputs such as D_XOR_1 & D_XOR_2.i.e.

   D_XOR_1 = D_C_1 xor C_1 D_XOR_2 = D_C_2 xor C_2

   Step 5: The results having two 8-bit datas obtained after the xor operations are appended to get the 16-bit decoded data known as original data.

   DECODED_DATA = D_XOR_1 & D_XOR_2

   16-bit Cipher Data

   Bit seperator

   Bit seperator

   1-bit Right

   1-bit Right

   1-bit Right

   1-bit Right

   1S COMPLEMENT

   1S COMPLEMENT

   1S COMPLEMENT

   1S COMPLEMENT

   XOR

   XOR

   Chip code

   XOR

   XOR

   Chip code

   Append two 8-bit datas

   Append two 8-bit datas

   Chip code

   Chip code

   16-bit Original/Recovered

   Figure 2: Block diagram of decryption process

3. Simulation Results:

   Figure 3: Simulation Result of bit seperator

   Figure 4: Simulation Result of xor operation using chip_code_one

   Figure 5: Simulation Result of xor operation using chip_code_two

   Figure 6: Simulation Result of 1s complement operation corresponding to chip_code_one

   Figure 7: Simulation Result of 1s complement operation corresponding to chip_code_two

   Figure 8: Simulation Result of left rotate operation corresponding to chip_code_one

   Figure 9: Simulation Result of left rotate operation corresponding to chip_code_two

   Figure 10: Simulation Result of bit append operation giving rise to the desired 16-bit encrypted data

   Figure 11: Simulation Result of encryption process showing the output of encryption block

   Figure 12: Simulation Result of bit seperator

   Figure 13: Simulation Result of right rotate operation corresponding to chip_code_one

   Figure 14: Simulation Result of right rotate operation corresponding to chip_code_two

   Figure 15: Simulation Result of 1s complement operation corresponding to chip_code_one

   Figure 16: Simulation Result of 1s complement operation corresponding to chip_code_two

   Figure 17: Simulation Result of xor operation using chip_code_one

   Figure 18: Simulation Result of xor operation using chip_code_two

   Figure 19: Simulation Result of bit append operation giving rise to the desired 16-bit decrypted data

   Figure 20: Simulation Result of decryption process showing the output of decryption block

4. Conclusion:

   The work done in this paper based on the encryption and decryption of 16-bit data can be used in the digital communication technology for error free data transmission from one point to another point and to protect the confidentiality of sensitive data in transmission. Further research is being carried out to implement this design in the processor unit of computer.

5. References:

1. W.Stallings,Cryptography and Network Security, 2nd Edition, Prentice Hall.

2. Christof Paar, Jan Pelzl, "The Data Encryption Standard (DES) and Alternatives", free online lectures on Chapter-3 of "Understanding Cryptography, A Textbook for Students and Practitioners", Springer.

3. Bruce Schneir: Applied Cryptography, 2nd edition, John Wiley & Sons.

4. A.Litwin, Cryptography and Network Security LOS Alamitos,CA:IEEE computer society press.